Question 434897
x^2+y^2-9=0 list the domain, range, center, and radius
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Standard form for a circle: (x-h)^2+(y-k)^2=r^2, with (h,k) being the (x,y) coordinates of the center and r=radius.
x^2+y^2-9=0
x^2+y^2=9
As you can see, this is a standard form of the circle. Since you don't see (h,k), the coordinates of center are (0,0).  Radius square is given as 9, so the radius is the sqrt(9)=3
Center: (0,0)  
Radius: 3 
Domain:[-3,3]
Range:[-3,3]
See graph of circle below:
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y=+-(9-x^2)^.5
{{{ graph( 300, 300, -5, 5, -5, 5, (9-x^2)^.5,-(9-x^2)^.5) }}}